Many systems and structures perform under varying, and often extreme, conditions. For example, systems exposed to high heat conditions must perform their functions at high temperatures. Such extreme temperatures or other conditions are common for certain aircraft, such as high-speed airplanes, missiles, and spacecraft. Hypersonic missiles travel through the atmosphere at speeds in the Mach 5-7 range or higher, which may expose missile elements to stagnation temperatures of approximately 1400° C. or more for several minutes.
Performance of aircraft elements may be limited by such high temperatures. Radomes present exemplary design issues for such high temperature applications. Missile radome performance may be limited by temperature, as well as waveband transmittance, material, process maturity, and affordability. Radomes, thermal protection systems (TPS), and aircraft leading edges require high temperature capability over sustained periods, all-weather durability, and electrical and/or thermal performance characteristics at a reasonable cost.
Further, as missile systems assume multiple roles and become more autonomous, missile seekers need to detect, discriminate, and track a larger variety of targets. Targets may be detected at dissimilar frequencies, employ various forms of jamming and/or countermeasures, and reside in operational environments with differing amounts of clutter. Broadband radomes may allow multiple sensors for broadband detection, as well as more effective narrowband seekers, for example by allowing use of multiple seeker combinations without changing the radome and/or future use of alternative seekers without redesigning and replacing the radome itself.
Numerous and complex design considerations affect radomes, especially high-speed broadband radomes. Electrical properties include transmission loss, sidelobe degradation, boresight error, bandwidth, and polarization. Aerodynamic factors may comprise drag, heating and ablation, while mechanical concerns include weight, shock resistance, vibration, impact resistance, and material static strength. Material selection may affect dielectric loss, operating temperature, strength, impact resistance, and manufacturing tolerances. Also, RF signature, IR signature, and optical observance factors play a role in design. From an environmental standpoint, rain erosion, hail/bird impacts, static discharge, lightning strikes, temperature, moisture, fluids/fungus, and thermal shock are all factors that should be evaluated. Cost considerations can also affect the design and deployment of a radome, including costs associated with development, fabrication facilities, and testing.